Initiation

1. Initiation https://store.theartofservice.com/the-initiation-toolkit.html

2. Session Initiation Protocol • The Session Initiation Protocol (SIP) is a signaling communications protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP) networks. https://store.theartofservice.com/the-initiation-toolkit.html

3. Session Initiation Protocol • The protocol defines the messages that are sent between peers which govern establishment, termination and other essential elements of a call. SIP can be used for creating, modifying and terminating sessions consisting of one or several media streams. SIP can be use for two-party (unicast) or multiparty (multicast) sessions. Other SIP applications include video conferencing, streaming multimedia distribution, instant messaging, presence information, file transfer, fax over IP and online games. https://store.theartofservice.com/the-initiation-toolkit.html

4. Session Initiation Protocol • Originally designed by Henning Schulzrinne and Mark Handley in 1996, SIP has been developed and standardized in RFC 3261 under the auspices of the Internet Engineering Task Force (IETF) https://store.theartofservice.com/the-initiation-toolkit.html

5. Session Initiation Protocol • SIP works in conjunction with several other application layer protocols that identify and carry the session media. Media identification and negotiation is achieved with the Session Description Protocol (SDP). For the transmission of media streams (voice, video) SIP typically employs the Real-time Transport Protocol (RTP) or Secure Real-time Transport Protocol (SRTP). For secure transmissions of SIP messages, the protocol may be encrypted with Transport Layer Security (TLS). https://store.theartofservice.com/the-initiation-toolkit.html

6. Session Initiation Protocol - History • SIP was originally designed by Henning Schulzrinne and Mark Handley in 1996. In November 2000, SIP was accepted as a 3GPP signaling protocol and permanent element of the IP Multimedia Subsystem (IMS) architecture for IP-based streaming multimedia services in cellular systems. The IETF Network Working Group published RFC 3261 - as of 2013 the latest version of the specification - in June 2002. https://store.theartofservice.com/the-initiation-toolkit.html

7. Session Initiation Protocol - History • The U.S https://store.theartofservice.com/the-initiation-toolkit.html

8. Session Initiation Protocol - Protocol design • SIP employs design elements similar to the HTTP request/response transaction model. Each transaction consists of a client request that invokes a particular method or function on the server and at least one response. SIP reuses most of the header fields, encoding rules and status codes of HTTP, providing a readable text-based format. https://store.theartofservice.com/the-initiation-toolkit.html

9. Session Initiation Protocol - Protocol design • Each resource of a SIP network, such as a user agent or a voicemail box, is identified by a uniform resource identifier (URI), based on the general standard syntax also used in Web services and e-mail. A typical SIP URI is of the form: sip:username:password@host:port. The URI scheme used for SIP is sip:. https://store.theartofservice.com/the-initiation-toolkit.html

10. Session Initiation Protocol - Protocol design • If secure transmission is required, the scheme sips: is used and mandates that each hop over which the request is forwarded up to the target domain must be secured with Transport Layer Security (TLS) https://store.theartofservice.com/the-initiation-toolkit.html

11. Session Initiation Protocol - Protocol design • SIP works in concert with several other protocols and is only involved in the signaling portion of a communication session https://store.theartofservice.com/the-initiation-toolkit.html

12. Session Initiation Protocol - Protocol design • A motivating goal for SIP was to provide a signaling and call setup protocol for IP-based communications that can support a superset of the call processing functions and features present in the public switched telephone network (PSTN) https://store.theartofservice.com/the-initiation-toolkit.html

13. Session Initiation Protocol - Protocol design • SIP-enabled telephony networks can also implement many of the more advanced call processing features present in Signaling System 7 (SS7), though the two protocols themselves are very different https://store.theartofservice.com/the-initiation-toolkit.html

14. Session Initiation Protocol - Protocol design • Although several other VoIP signaling protocols exist (such as BICC, H.323, MGCP, MEGACO), SIP is distinguished by its proponents for having roots in the IP community rather than the telecommunications industry. SIP has been standardized and governed primarily by the IETF, while other protocols, such as H.323, have traditionally been associated with the International Telecommunication Union (ITU). https://store.theartofservice.com/the-initiation-toolkit.html

15. Session Initiation Protocol - Protocol design • The first proposed standard version (SIP 1.0) was defined by RFC 2543. This version of the protocol was further refined to version 2.0 and clarified in RFC 3261, although some implementations are still relying on the older definitions.[specify] https://store.theartofservice.com/the-initiation-toolkit.html

16. Session Initiation Protocol - Network elements • SIP also defines server network elements. Although two SIP endpoints can communicate without any intervening SIP infrastructure, which is why the protocol is described as peer-to-peer, this approach is often impractical for a public service. RFC 3261 defines these server elements. https://store.theartofservice.com/the-initiation-toolkit.html

17. Session Initiation Protocol - User Agent • A SIP user agent (UA) is a logical network end-point used to create or receive SIP messages and thereby manage a SIP session. A SIP UA can perform the role of a User Agent Client (UAC), which sends SIP requests, and the User Agent Server (UAS), which receives the requests and returns a SIP response. These roles of UAC and UAS only last for the duration of a SIP transaction. https://store.theartofservice.com/the-initiation-toolkit.html

18. Session Initiation Protocol - User Agent • A SIP phone is a SIP user agent that provides the traditional call functions of a telephone, such as dial, answer, reject, hold/unhold, and call transfer https://store.theartofservice.com/the-initiation-toolkit.html

19. Session Initiation Protocol - User Agent • In SIP, as in HTTP, the user agent may identify itself using a message header field 'User-Agent', containing a text description of the software/hardware/product involved. The User-Agent field is sent in request messages, which means that the receiving SIP server can see this information. SIP network elements sometimes store this information, and it can be useful in diagnosing SIP compatibility problems. https://store.theartofservice.com/the-initiation-toolkit.html

20. Session Initiation Protocol - Proxy server • An intermediary entity that acts as both a server (UAS) and a client (UAC) for the purpose of making requests on behalf of other clients https://store.theartofservice.com/the-initiation-toolkit.html

21. Session Initiation Protocol - Registrar • A registrar is a SIP endpoint that accepts REGISTER requests and places the information it receives in those requests into a location service for the domain it handles. The location service links one or more IP addresses to the SIP URI of the registering agent. The URI uses the sip: scheme, although other protocol schemes are possible, such as tel:. More than one user agent can register at the same URI, with the result that all registered user agents receive the calls to the URI. https://store.theartofservice.com/the-initiation-toolkit.html

22. Session Initiation Protocol - Registrar • SIP registrars are logical elements, and are commonly co-located with SIP proxies. But it is also possible and often good for network scalability to place this location service with a redirect server. https://store.theartofservice.com/the-initiation-toolkit.html

23. Session Initiation Protocol - Redirect server • A user agent server that generates 3xx (Redirection) responses to requests it receives, directing the client to contact an alternate set of URIs. The redirect server allows proxy servers to direct SIP session invitations to external domains. https://store.theartofservice.com/the-initiation-toolkit.html

24. Session Initiation Protocol - Session border controller • Session border controllers Serve as middle boxes between UA and SIP servers for various types of functions, including network topology hiding, and assistance in NAT traversal. https://store.theartofservice.com/the-initiation-toolkit.html

25. Session Initiation Protocol - Gateway • Gateways can be used to interface a SIP network to other networks, such as the public switched telephone network, which use different protocols or technologies. https://store.theartofservice.com/the-initiation-toolkit.html

26. Session Initiation Protocol - SIP messages • SIP is a text-based protocol with syntax similar to that of HTTP. There are two different types of SIP messages: requests and responses. The first line of a request has a method, defining the nature of the request, and a Request-URI, indicating where the request should be sent. The first line of a response has a response code. https://store.theartofservice.com/the-initiation-toolkit.html

27. Session Initiation Protocol - SIP messages • REGISTER: Used by a UA to indicate its current IP address and the URLs for which it would like to receive calls. https://store.theartofservice.com/the-initiation-toolkit.html

28. Session Initiation Protocol - SIP messages • INVITE: Used to establish a media session between user agents. https://store.theartofservice.com/the-initiation-toolkit.html

29. Session Initiation Protocol - SIP messages • BYE: Terminates a session between two users in a conference. https://store.theartofservice.com/the-initiation-toolkit.html

30. Session Initiation Protocol - SIP messages • OPTIONS: Requests information about the capabilities of a caller, without setting up a call. https://store.theartofservice.com/the-initiation-toolkit.html

31. Session Initiation Protocol - SIP messages • A new method has been introduced in SIP in RFC 3262: https://store.theartofservice.com/the-initiation-toolkit.html

32. Session Initiation Protocol - SIP messages • Provisional (1xx): Request received and being processed. https://store.theartofservice.com/the-initiation-toolkit.html

33. Session Initiation Protocol - SIP messages • Success (2xx): The action was successfully received, understood, and accepted. https://store.theartofservice.com/the-initiation-toolkit.html

34. Session Initiation Protocol - SIP messages • Redirection (3xx): Further action needs to be taken (typically by sender) to complete the request. https://store.theartofservice.com/the-initiation-toolkit.html

35. Session Initiation Protocol - SIP messages • Client Error (4xx): The request contains bad syntax or cannot be fulfilled at the server. https://store.theartofservice.com/the-initiation-toolkit.html

36. Session Initiation Protocol - SIP messages • Server Error (5xx): The server failed to fulfill an apparently valid request. https://store.theartofservice.com/the-initiation-toolkit.html

37. Session Initiation Protocol - SIP messages • Global Failure (6xx): The request cannot be fulfilled at any server. https://store.theartofservice.com/the-initiation-toolkit.html

38. Session Initiation Protocol - Transactions • SIP makes use of transactions to control the exchanges between participants and deliver messages reliably. The transactions maintain an internal state and make use of timers. Client Transactions send requests and Server Transactions respond to those requests with one-or-more responses. The responses may include zero-or-more Provisional (1xx) responses and one-or-more final (2xx-6xx) responses. https://store.theartofservice.com/the-initiation-toolkit.html

39. Session Initiation Protocol - Transactions • Transactions are further categorized as either Invite or Non-Invite. Invite transactions differ in that they can establish a long-running conversation, referred to as a Dialog in SIP, and so include an acknowledgment (ACK) of any non-failing final response (e.g. 200 OK). https://store.theartofservice.com/the-initiation-toolkit.html

40. Session Initiation Protocol - Transactions • Because of these transactional mechanisms, SIP can make use of un-reliable transports such as User Datagram Protocol (UDP). https://store.theartofservice.com/the-initiation-toolkit.html

41. Session Initiation Protocol - Transactions • If we take the above example, User1’s UAC uses an Invite Client Transaction to send the initial INVITE (1) message https://store.theartofservice.com/the-initiation-toolkit.html

42. Session Initiation Protocol - Instant messaging and presence • The Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIMPLE) is the SIP-based suite of standards for instant messaging and presence information. MSRP (Message Session Relay Protocol) allows instant message sessions and file transfer. https://store.theartofservice.com/the-initiation-toolkit.html

43. Session Initiation Protocol - Conformance testing • TTCN-3 test specification language is used for the purposes of specifying conformance tests for SIP implementations. SIP test suite is developed by a Specialist Task Force at ETSI (STF 196). The SIP developer community meets regularly at the SIP Forum SIPit events to test interoperability and test implementations of new RFCs. https://store.theartofservice.com/the-initiation-toolkit.html

44. Session Initiation Protocol - Applications • The market for consumer SIP devices continues to expand; there are many devices such as SIP Terminal Adapters, SIP Gateways, and SIP Trunking services providing replacements for ISDN telephone lines. https://store.theartofservice.com/the-initiation-toolkit.html

45. Session Initiation Protocol - Applications • Many VoIP phone companies allow customers to use their own SIP devices, such as SIP-capable telephone sets, or softphones. https://store.theartofservice.com/the-initiation-toolkit.html

46. Session Initiation Protocol - Applications • SIP-enabled video surveillance cameras can make calls to alert the owner or operator that an event has occurred; for example, to notify that motion has been detected out-of-hours in a protected area. https://store.theartofservice.com/the-initiation-toolkit.html

47. Session Initiation Protocol - Applications • SIP is used in audio over IP for broadcasting applications where it provides an interoperable means for audio interfaces from different manufacturers to make connections with one another. https://store.theartofservice.com/the-initiation-toolkit.html

48. Session Initiation Protocol - SIP-ISUP interworking • A Session Initiation Protocol (SIP) connection is a Voice over Internet Protocol (VoIP) service offered by many Internet telephony service providers (ITSPs) that connects a company's private branch exchange (PBX) telephone system to the public switched telephone network (PSTN) via the Internet. https://store.theartofservice.com/the-initiation-toolkit.html

49. Session Initiation Protocol - SIP-ISUP interworking • Using a SIP connection may simplify administration for the organization as the SIP connection typically uses the same Internet access that is used for data. This often removes the need to install Basic Rate Interface (BRI) or Primary Rate Interface (PRI) telephone circuits. https://store.theartofservice.com/the-initiation-toolkit.html

50. Session Initiation Protocol - Deployment issues • If the call traffic runs on the same connection with other traffic, such as email or Web browsing, voice and even signaling packets may be dropped and the voice stream may be interrupted. https://store.theartofservice.com/the-initiation-toolkit.html